Pressure release and relief valve



March 21, 1961 w. VALLEE PRESSURE RELEASE AND RELIEF VALVE Filed April 19, 1956 INVENTOR- ZZZKUQZZM/ 2,975,803 PRESSURE RELEASE AND RELIEF VALVE Wendell L. Vallee, Sheboygan, Wis., assignor to Blackhawk Mfg. Co., West Allis, Wis, a corporation of Wisconsin Filed Apr. 19, 1956, Ser. No. 579,309

1 Claim. (Cl. 137599.2)

The present invention relates generally to improvements in the art of hydraulics, and relates more particularly to improvements in the construction and operation of hydraulic power units such as hydraulic vehicle jacks.

A primary object of this invention is to provide an improved hydraulic power applying device which is extremely simple and compact in construction and which is moreover highly efficient in operation.

In the manufacture of hydraulic jacks and the like, it is common practice to provide a manually operable valve interposed between the pressure side of the ram cylinder and the fluid reservoir for releasing the pressure below the ram to thereby permit the ram to return to non-working condition. It is also customary to provide an automatically operable valve between the pressure side of the ram cylinder and the reservoir and responsive to predetermined high pressure conditions in the ram cylinder for relieving the pressure therein when it exceeds certain limits. lease valves and relief valves are ordinarily formed as two entirely independent units, each requiring separate machining and assembly operations and each being separately accessible for inspection and repair.

It is therefore a more specific object of my present invention to provide an improved hydraulic jack or the like which embodies a combined pressure release and relief valve, thus obviating the above-mentioned objections to prior devices of this general type.

Another specific object of the invention is to provide an improved unitary pressure release and relief valve for hydraulic power tools which is conveniently located and wherein all parts are readily accessible from a single station for inspection, replacement, or repair without need for dismantling the tool.

Another specific object of this invention is to provide an improved pressure release valve for hydraulic jacks or the like which has an extremely simple and readily accessible relief valve embodied directly therein.

Still another specific object of my present invention is to provide an improved combined pressure release and relief valve for hydraulic tools in which the relief valve is adjustable to respond to certain conditions and is readily accessible to rapidly effect desired readjustments therein.

A further specific object of the present invention is to provide an improved unitary valve interposed between the displacement chamber and the liquid reservoir of a hydraulic tool and which is automatically operable to relieve abnormally high pressure conditions from within the displacement chamber while being manually releasable for entirely releasing the pressure therefrom.

These and other specific objects and advantages of However, these so-called re-- the invention will become apparent from the following detailed description.

A clear conception of the various features constituting the present improvement, and of the mode of constructing and of utilizing a hydraulic jack assemblage embodying the same, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the several views.

Fig. 1 is a fragmentary part sectional side view of a typical hydraulic jack embodying the invention;

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Fig. 2 is a transverse vertical section through the jack and the pump therefor;

Fig. 3 is an enlarged fragmentary section through the portion of the pump base which houses the improved release and relief valve also shown in section;

Fig. 4 is an enlarged transverse section through a somewhat modified valve cage; and

Fig. 5 is a similarly enlarged transverse section through another somewhat modified valve cage.

While the invention has been specifically shown and described herein as being embodied in and particularly applicable to a hydraulic jack of a particular type, the improvements are obviously advantageously applicable to hydraulic tools generally wherein a ram or piston member is actuated by hydraulic pressure built up within a displacement chamber and in which it is desired to release the pressure at the will of an operator while also providing means to relieve abnormally high pressures. It is also contemplated that certain specific descriptive terms used herein shall be given the broadest possible interpretation consistent with the disclosure.

Referring to the drawing, the typical hydraulic jack shown therein as embodying the present improved combined release and relief valve comprises, in general, a base or supporting member 8, a work performing member 0r ram 9 reciprocable toward and away from the base member 8, means such as a tube 10 suitably secured to the base member 8 and projecting therefrom to form a displacement chamber or cylinder 11'for the ram 9, means such as a tube 12 of greater diameter than the tube 10 secured to the base 8 concentric with the tube 10 to form an annular liquid reservoir 13, closed at its upper end by an annular cylinder head 14, means in the form of a pump 15 composed of a piston 16 reciprocable within a cylinder 17 by means of a handle 18 for supplying liquid under pressure from the reservoir 13 to the displacement chamber 11, the displacement chamber 29 of the pump being in communication with the liquid reservoir 13 by way of a conduit 19 past an inlet valve 20 and being in communication with the displacement chamber 11 by way of a conduit 21 past a spring pressed valve 22.

The hydraulic jack thus far described is of ordinary construction, and the ram 9 carries a suitable packing 24 at the lower end thereof while the cylinder head 14 is provided with a packing 25 embracing the ram. The ram or reciprocable piston 9 may additionally be provided with a suitable work engaging bearing member 26 at its upper end, and a vent opening 27 may be formed in the cylinder head 14 to vent the upper end of the chamber 11 to the upper portion of the reservoir 13. The pump cylinder 17 and pump piston 16 may also be provided with suitable packings to prevent leakage, and the pump handle 18 is pivotally secured to the upper end of the piston 16 as at27 in the usual manner, with the handle 18 being fulcrumed as at 28 to thereby provide for reciprocation of the pump piston 16 upon actuation of the handle 18. V

In accordance with the present invention, the base member 8 is provided with a suitable pressure releaserelief passage formed by the bores 30, 31 forming branches angularly disposed relative to each other, the branch 30 communicating with the displacement chamber 11 and being provided with a counterbore 32 to form an annular valve seat 33 and the branch 31 communicating with the liquid reservoir 13. The improved valve 34 is disposed within the counterbore 32 and is adapted to seat against the annular seat 33 to close the passage 30, 31, and manually manipulatable means such as an axially movable spindle 35 is provided for selectively urging the valve 34 to closed position or for manually releasing the same from its seat to thereby release the pressure from within the displacement chamber 11. To prevent leakage, the spindle 35 is provided with a suitable packing 36 retained in position by means of a packing gland 37, the spindle having screw threaded coaction with the packing gland 37 and being provided with a manipulating handle 38 for facilitating turning.

As shown, the manually operable release valve 34 is hollow and has a conduit or port 39 leading from the interior of the valve to the branch 30 or high pressure side of the release-relief passage and a second conduit or port 40 leading from the interior of the valve 34 to the branch 31 or low pressure side of the passage. Housed within the hollow manually operable release valve 34 is a second valve 41 preferably in the form of a ball constantly urged into seated position closing the conduit or port 39 by means of a compression spring 42. While the valve 34 is shown as being'in the form of a separate hollow cage or cartridge, it may be formed integral with and as a part of the stem 35, but as shown it is preferably closed at one end by a set screw 43 forming a bearing for the spring 42 and permitting adjustments in the compression thereof to thereby vary the limits within which the valve 41 will automatically respond, as shown in Figs. 4 and 5, or closed at one end by a snap ring 47 as in Fig. 3, which would not necessarily provide for adjustment of the spring 42.

As shown in Figs. 3, 4 and 5, the outside diameter of the valve 34 is somewhat less than the diameter of the counterbore 32 to thereby permit circulation of fluid around the valve and through the passages 30, 31 when the valve stem 35 is moved axially outwardly to release the valve 34 from its seat; and to guide the valve 34 in its movement within the counterbore, the valve may be formed with an annular series of ribs 45 or the like. The relief valve 41 may assume various forms as also shown in Figs. 3, 4 and 5, and if desired, a reciprocable guide stem 46 for the spring 42 may be provided, the stem being guided within a suitable bore in the set screw 43.

In operation, the spindle 35 is first manually rotated so as to firmly urge the valve 34 toward and against the valve seat 33 to thereby close the passage formed by the bores 30, 31. The jack is then properly positioned with respect to the article to be worked upon, and the pump 15 is actuated by the handle 18 to cause reciprocation of Y the pump displacement chamber 29 when the plunger,

is raised and valve 20 will close while the valve 22 is forced open to conduct liquid under pressure from the pump displacement chamber 29 through the conduit 21 upon each return stroke of the plunger. The liquid thus pumped under pressure to the displacement chamber 11 below the ram 9 thereby causes the ram 9 to move outwardly away from the base 8 and causes the ram to perform its work. If the pressure within the displacement chamber 11 becomes abnormally excessive, the valve 41 will be acted upon automatically and when the pressure within the branch 30 of the passage leading to the displacement chamber 11 is suflicient to overcome the action of the spring 42, the valve 41 will unseat and the high pressure fluid will be permitted to flow into the hollow valve 34 through theports 39, 40 and into the oil reservoir 13 through the branch 31. As soon as the pressure within the chamber 11 returns below the maximum desired pressure, the spring 42 will again cause the valve 41 to return to seated or closed position, and the action thus described is entirely automatic and is dependent upon the adjustmentsin the compression of the spring 42. When the work has been completed and it is desired to return the ram 9 to nested position within the chamber 11 as shown in the drawings, it is only necessary to manually rotate the spindle 35 by means of the handle 38 so as to retract the same outwardly thus permitting the valve 34 to-be released from its seat 33 so that the l 4 high pressure fluid may then flow freely through the passage formed by the bores 30, 31 and past and around the valve 34 back to the reservoir 13.

From the foregoing detailed description, it is believed apparent that the present invention contemplates the provision of a novel and improved unitary release and relief valve which is extremely simple and compact and which is highly efficient in operation. It is obvious that the branches 30, 31 forming the release-relief passage may be readily formed, and by virtue of the combined releaserelief valve unit separate provision for these valves need not be made and separate machining operations are thereby eliminated. Moreover, both the release valve 34 and the relief valve 41 are readily accessible for adjust ment or repair merely upon removal of the spindle 35 in an obvious manner, and dismantling of the jack for servicing of the valves is accordingly eliminated. As heretofore indicated, the valve 34 may either be in the form of a cartridge or cage formed independently of the spindle 35, or it may be formed integral with the spindle or secured thereto as by means of screw threads, and as shown it is preferable to provide means such as the set screw 43 for adjusting the spring tension. It is also obvious that the improved combined unitary release and relief valve assemblage may be readily incorporated in other hydraulic power tools and its use is not necessarily limited to a hydraulic jack of the type herein shown. It is also apparent that the base 8 may assume any desired form, and while the valve 34 need not be located within the base as shown, the base does nevertheless provide a suitable housing therefor.

It is not desired or intended to limit this invention to the exact details of construction or the precise mode of use herein shown and described since various modifications within the scope of the appended claim may occur to persons skilled in the art to which this invention pertains.

I claim:

A combination pressure release and relief valve assembly comprising, a casing member having a bore of uniform diameter one end of which is provided with a seat in open communication past a port with a high pressure liquid source while its opposite end portion is sealed by a gland having internal screw threads and its medial portion is in open communication through a return conduit with a low pressure liquid supply, a unitary cupshaped release valve cartridge directly slidably confined within said bore and having a tapered end sealingly cooperable with said seat and also having therein a passage in open communication with said port and an opening in open communication with said conduit, a spring pressed ball relief valve housed within said cartridge and coacting with said port to establish communication between said source and said supply whenever the pressure at said source becomes abnormally high, and a longitudinally adjustable spindle having thereon external screw threads coacting with said gland threads and being provided with a cylindrical inner end portion also directly slidable within said casing bore and abutting the end of said cartridge remote from its tapered end.

References Cited in the file of this patent UNITED STATES PATENTS 433,543 Schreidt Aug. 5, 1890 807,269 Hildebrand Dec. 12, 1905 1,706,309 Miller Mar. 19, 1929 1,771,879 Dowd et al July 29, 1930 2,018,506 Walker Oct. 22, 1935 2,107,970 Wells Feb. 8, 1938 2,548,903 Mueller Apr. 17, 1951 2,577,539 Page Dec. 4, 1951 2,713,773 Sutton July 26, 1955 FOREIGN PATENTS 596,751 Great Britain Jan. 9, 1948 

